Apparatus for acetylene production by partial combustion of hydrocarbons



G. FAUSER COMBUSTION 0F HYDROOARBONS Flled Oct. 22, 1962 APPARATUS FORACETYLENE PRODUCTION BY PARTIAL April 19, 1966 United States Patent,639/ 61 4 Claims. '(Cl. 23-277) My invention relates to the productionof acetylene by partial combustion of gaseous hydrocarbons, particularlymethane or its higher homologues, with oxygen.

The equipment used for such production comprises a mixer to whichmethane and oxygen, separately preheated, are supplied, and a reactionchamber wherein the methane burns in form of an inverted flame which israpidly extinguished with a water jet.

vIn order to prevent propagation of the flame from the combustionchamber to the mixing chamber, a distributor is interposed. It consistsof a properly cooled steel plate vertically traversed by numerousparallel tubes in which the gas flow has a speed higher than the speedof flame propagation.

As the tubes are parallel, the speed of gas in the zone closely abovethe top surface of the distributor will necessarily be lower than thespeed of the flame propagation. Thus, if accidental causes lead toignition of the mixture upstream of the distributor, all of the gaseousmasscontained in the mixing chamber, may also become ignited, thusresulting in irreparable damages to the apparatus.

It is an object of my invention to obviate such danger. My inventionessentially consists of providing a gas distributor, which separates themixing chamber from the combustion chamber, so that the speed of gasupstream the distributor is higher than the speed of flame propagation,and is illustrated by the drawing. V

Methane or a higher homolog thereof and oxygen, respectively preheatedin heaters 1 and 2, are introduced from above to mixer 3, at a speedgreater than that of flame propagation, so that in the event of ignitionthe flame could not remain in the tube but would be immediately blowndown. The distributor 4 is formed by two steel plates, which arepreferably spherical, connected by numerous steel tubes 13; the topplate 9 has a smaller surface than the bottom plate 10. When the steelplates are spherical, the tubes connecting the two plates diverge.

The ratio between the diameter of the top and bottom plates is socalculated that the speed of gas near the top plate and in theconnecting tubes is higher than the speed of flame propagation, whereasthe speed of gas in the combustion chamber is much less than the speedof flame propagation. With my apparatus as described, it is possible tomaintain a constant and regular flame which remains at the lower surfaceof the distributor.

The relationship existing between the upper and lower surface areas ofthe pipe-distributor of the burner is as follows (said areas beingproportional to the squares of the respective diameters d and D):

wherein d and D are respectively the diameter of the upper and lowersurfaces and 7 is the ratio between the square of the diameters, and isgreater than 0 but less than 1 and represents a fraction which is thereciprocal of the pressure, that is, a function f=f'( P) and is anexperimental correlation giving 3 a numerical value equal to PatentedApr. 19, 1966 in the meaning that with an increase of pressure there isa reduction of the factor f.

The r nixture of hydrocabron and oxygen affords easier preignitions andhigher velocities of flame propagation, theh gher the cracking pressure.Hence the higher the cracking pressure, the smaller must ratio d /D beand correspondingly the greater the velocity of the gas entermg at topof the distributor with respect to the velocity of the gas leaving atbottom where the flame appears. TiJlS ratio preferably assumes valuescomprised within the following limits:

Water is circulated under pressure by pump 5 between the d1vergingtubes, in order to ensure the cooling of the lower plates. The coolingwater after being heated is recycled through line 12 to storage tank 14from where small quantities of steam are permitted to enter the oxygenpreheater 2.

Other variations of the distribution are possible provided therelationship of I is maintained. For instance, the plates need not bespherical but could be planar. Alternatively, for instance, thefollowing structures may be adopted: (a) a structure quite analogous tothat described above but wherein the pipes for the outflow of the gasmixture project from the top plate of the distributor and the spacesbetween the pipes are filled with refractory; (b) another structurehaving steel pipes 13 embedded over their whole lengths in a suitablerefractory whence neither the top metal plate nor the bottom metal plateare any longer needed: in that case the line 11 may be connecteddirectly to the storage vessel 14, no cooling being any more required;(c) a further structure with which not only the top and bottom platesbutalso the steel pipes 13 are dispensed with, the conduits for the gasmixture being provided in the very refractory; here too the line 11leads directly to the storage vessel 14.

By using, for example, water at a pressure, of say 16 atmospheres whichcorresponds to a boiling temperature of 200 C., the mechanical stresseson the cooled metal walls, because of thermal expansion, are much lessthan by using cold water.

One of the more troublesome difliculties in the production of acetylenethrough partial combustion of methane or other hydrocarbons with oxygen,is the formation of carbon black. I have found that the formation ofcarbon black may be effectively reduced if a small quantity of steam isadded to the reacting gases. For example, the addition of 10 kg. ofsteam per Nm. of methane is suflicient for reducing to Ma the productionof carbon black without any effect on the acetylene yield. The steam maybe added to the oxygen and/ or methane prior to their reentry intopreheaters 1 and 2 or into the mixer 33. The quantity of steam may varybetween 2 and 20 kg. per 100 Nm. of CH, although about 10 kg. ispreferable. The presence of steam also gives greater safety againstself-ignition of the methane-oxygen mixture particularly when underpressure, thus reducing the probability of a premature gas combustion inthe mixing chamber.

The technique, generally used in the conventional acetylene productionprocess for stabilizing the flame, consists in introducing smallquantities of oxygen (secondary) through the cooled walls of thecombustion chamber, near the reaction priming zone; but it is known thatsuch a technique has the effect of greatly reducing the (a)methane-l-primary and secondary oxygen (b) methane-l-primary andsecondary oxygen-l-steam (c) methane-i-primary oxygen andhydrogen-l-secondary oxygen are shown by the following proportionsbetween the flow rates of the reactants employed and the respective flowrates of the reactants employed and the respective results obtained;wherein Nm. is cubic meters calculated at normal conditions:

Table Case (a) (b) Flow rate of CH Nmfilhr 250 2b0 360 Temperature of CHpreheating, C 550 5-50 550 Flow rate of primary 0;, Nun /hr. .0. 140 145210 Temperature of prim.0 preheating, C Flow rate of secondary 0g,Nmfi/hr Temperature of secondary 0 C Flow rate of steam, lag/hrPreheating temperature of steam, 0 Flow rate of Hz, Nmfi/hr Temperatureof H 0 Flow rate of Oz with H Nmfilhrn Temperature of Oz with Hg, C

Cracking pressure. abs. atm 4 4 4 Carbon black content in quenching er,0. 45 0. 15 0. 04

Acetylene yield. Kg. of 02H; 16.8 17.0 17. 8

100 Nm. of OH,

100 Nmr of on;

I claim:

1. In an apparatus for the production of acetylene by the partialcombustion of hydrocarbons with oxygen having a gas mixing chamber and acombustion chamber; a gas distributor interconnecting the gas mixingchamber and the combustion chamber, said gas distributor comprising alower metalplate, an'upper metal plate and tubes of constant diameterinterconnecting said plates for gas passage from the gas mixing chamberto the combustion chamber, the area of the upper of said metal platesbeing from 0.2 to 0.8 the area of the lower of said plates,

which are spherical and concentric, said tubes being evenly spaced anddiverging from the upper to the lower plates, a water jacket about thetubes and disposed between the plates for introducing water underpressure to cool said tubes and produce steam, a row of oxy-hydrogenburners at the lower of said plates to stabilize the flame produced bysaid partial combustion, and quench means downstream of saidoxy-hydrogen burners for quenching said combustion.

2. The apparatus of claim 1, which includes means for passing the steam,produced in the Water jacket, to the gas mixing chamber.

3. In an apparatus for the production of acetylene by the partialcombustion of hydrocarbons with oxygen having a gas mixing chamber and acombustion chamber; a gas distributor interconnecting the gas mixin-gchamber and the combustion chamber, said gas distributor comprising alower metal plate, an upper metal plate and tubes of constant diameterinterconnecting said plates for gas passage from the gas mixing chamberto the combustion chamber, the area of the upper of said metal platesbeing from 0.2 to 0.8 the area of lower of said plates, which are planarand parallel, said tubes being evenly spaced and diverging from theupper to the lower plates, a water jacket about the tubes and disposedbetween the plates for introducing water under pressure to cool saidtubes and produce steam, a row of oxy-hydrogen burners at the lower ofsaid plates to stabilize the flame produced by said partial combustion,and quench means downstream of said oxy-hydrogen burners for quenchingsaid combustion.

4. The apparatus of claim 3 which contains means for passing the steam,produced in the water jacket, to the gas mixing chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,113,171 10/1914Creelman 158-99 1,146,724 7/1915 Lucke 158-99 1,773,592 8/1930 McDaniel158-104 2,520,149 8/1950 Keeling 260-679 2,719,184 9/1955 Kosbahn et a1.260-679 3,019,271 1/1962 Braconier et a1. 260679 3,069,248 12/1962Braconier et al. 260679 MORRIS O. WOLK, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

1. IN A APPARATUS FOR THE PRODUCTION OF ACETYLENE BY THE PARTIALCOMBUSTION OF HYDROCARBONS WITH OXYGEN HAVING A GAS MIXING CHAMBER AND ACOMBUSTION CHAMBER; A GAS DISTRIBUTOR INTERCONNECTING THE GAS MIXINGCHAMBER AND THE COMBUSTION CHAMBER, SAID GAS DISTRIBUTOR COMPRISING ALOWER METAL PLATE, AN UPPER METAL PLATE AND TUBES OF CONSTANT DIAMETERINTERCONNECTING SAID PLATES FOR GAS PASSAGE FROM THE GAS MIXING CHAMBERTO THE COMBUSTION CHAMBER, THE AREA OF THE UPPER OF SAID METAL PLACESBEING FROM 0.2 TO 0.8 THE AREA OF THE LOWER OF SAID PLATES, WHICH ARESPHERICAL AND CONCENTRIC, SAID TUBES BEING EVENLY SPACED AND DIVERGINGFROM THE UPPER TO THE LOWER PLATES, A WATER JACKET ABOUT THE TUBES ANDDISPOSED BETWEEN THE PLATES FOR INTRODUCING WATER UNDER PRESSURE TO COOLSAID TUBES AND PRODUCE STEAM, A ROW OF OXY-HYDROGEN BURNERS AT THE LOWEROF SAID PLATES TO STABILIZE THE FLAME PRODUCED BY SAID PARTIALCOMBUSTION, AND QUENCH MEANS DOWNSTREAM OF SAID OXY-HYDROGEN BURNERS FORQUENCHING SAID COMBUSTION.